STOCK BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average Grant Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price		$ 528,000	$ 0
Restricted Stock Awards [Member]
Weighted Average Grant Date Fair Value
Costs are expected to be recognized over a weighted average period		1 year 2 months 1 day	1 year 6 months 22 days
LMI Aerospace, Inc. 2005 Long-Term Incentive Plan [Member]
Weighted Average Grant Date Fair Value
Compensation expense		$ 485	$ 1,284	$ 1,850
LMI Aerospace, Inc. 2005 Long-Term Incentive Plan [Member] | Restricted Stock Awards [Member]
Shares
Outstanding beginning balance (in shares)		253,434
Granted (in shares)		0
Vested (in shares)		(53,846)
Forfeited (in shares)		(31,038)
Outstanding ending balance (in shares)		168,550	253,434
Weighted Average Grant Date Fair Value
Outstanding beginning balance (in dollars per share)		$ 14.54
Granted (in dollars per share)		0.00
Vested (in dollars per share)		17.89
Forfeited (in dollars per share)		14.19
Outstanding ending balance (in dollars per share)		$ 13.53	$ 14.54
Unrecognized compensation costs		$ 513	$ 1,762
Fair value of restricted stock awards that vested		$ 527	1,559	$ 1,083
LMI Aerospace, Inc. 2015 Long-term Incentive Plan - Non Qualified Deferred Compensation Plan for Senior Executives and Outside Directors [Member] | Restricted Stock Awards [Member]
Shares
Outstanding ending balance (in shares)		6,129
LMI Aerospace, Inc. 2015 Long-term Incentive Plan [Member]
Weighted Average Grant Date Fair Value
Compensation expense		$ 992	$ 303
LMI Aerospace, Inc. 2015 Long-term Incentive Plan [Member] | Restricted Stock Awards [Member]
Shares
Outstanding beginning balance (in shares)		61,801
Granted (in shares)		277,552
Vested (in shares)	[1]	(55,672)
Forfeited (in shares)		(9,553)
Outstanding ending balance (in shares)		274,128	61,801
Weighted Average Grant Date Fair Value
Outstanding beginning balance (in dollars per share)		$ 9.79
Granted (in dollars per share)		8.50
Vested (in dollars per share)		9.79
Forfeited (in dollars per share)		9.43
Outstanding ending balance (in dollars per share)		$ 8.46	$ 9.79
Unrecognized compensation costs		$ 1,510	$ 303
Costs are expected to be recognized over a weighted average period		1 year 9 months 18 days	6 months 4 days

[1] Excludes 6,129 shares for which service requirements are met that remain subject to deferral at December 31, 2016 pursuant to the LMI Aerospace, Inc. Non-Qualified Deferred Compensation Plan for Senior Executives and Outside Directors.